The invention concerns a tool member for removing a drill core formed of a gripping part and a receptacle part for engaging and removing the drill core.
In the creation of a large-diameter bore hole a drill bit is used, for example, as is described in U.S. Pat. No. 5,651,646. Using such a drill bit having a tubular carrier member, an annular cut out of a defined depth can be made in a receiving material. When the annular cutout is completed, a drill core is produced, which remains within the drill bit when an annular bore hole is made and the bit is withdrawn from the receiving material. In the case of a blind bore hole the drill core remains in the bore hole; that is, the drill core is still fixed to the remaining part of the receiving material, in the base portion of the cutout.
Such a drill core that is still fixedly attached to the remaining part of the receiving material is usually removed from the bore hole using various tools such as, for example, a turnscrew, or a davit or lifting dogs. Larger diameter drill cores are conventionally removed by inserting a dowel into the freely accessible face side of the drill core which can then be gripped by an appropriately powerful lifting tool.
Particularly in the case of the drill cores with a diameter of approximately 40 cm there is the risk that the drill core might break up and a drill core stump remains attached in the base of the bore hole in the receiving material. Such a bore core stump cannot be removed using the aforementioned tools.
The receiving material in which the annular cutout is formed may be rock, masonry or a similar hard material.
The object of the invention is to provide a tool member for removing a drill core from a bore hole in a receiving material and with which the entire drill core can be easily, safely and rapidly removed from the bore hole and which can be economically manufactured.
The object is achieved by a tool for removing a drill core having a gripping region and a receptacle region arranged to hold and remove the drill core from the receiving material.
By arranging an axially extending member into a receptacle region with at least half of a circular circumference, a tipping removal annular cutout formed in the receptacle region and extending about the drill core along the longitudinal axis of the bore hole is possible. When this is done, the drill core in the bottom zone of the annular cutout is broken off from the remaining part of the receiving material. On withdrawal of the tool according to the invention from the cutout, the drill core so detached remains in the receptacle region of the tool.
So that the drill core removed from the bore hole can be removed from the receptacle region of the tool, the receptacle region preferably extends around approximately half of the circular annular shaped circumference of the tool member.
The length of the receptacle region depends on the length of the drill core that must be removed. For practical purposes the receptacle region extends over 0.4 to 0.75 times the overall length of the tool member. The gripping region is preferable fashioned in a tubular shape so that the tool member can be gripped well in the operator""s hand.
Due to manufacturing considerations, a pair of swivel arms are formed as part of the tool member.
Particularly when removing a drill core from an essentially vertically arranged bore hole which, for example, was drilled into the receiving material, both swivel arms hold the drill core in the receptacle region. The swivel arms preferably exhibit free ends facing the gripping end and project into the inside diameter of the member, so that the swivel arms can act as holding hooks.
Instead of tipping the tool out of the longitudinal axis of the bore hole, a lateral force can be applied to the drill core at the bottom of the annular cutout relative to the longitudinal axis of the bore hole using a ramp. Preferably, the ramp is located in the region of the swivel arms and projects into the inner diameter of the tool member. The height of the ramp increases in the direction of the gripping region. The ramp is particularly well suited to breaking the part of the already broken up drill core or drill core stump fragments that can no longer be removed using conventional tools.
To be able to prevent a removed drill core from falling out of the free end of the tool member in the gripping region, the tool member is expediently provided with a closure element at the free end of the gripping region.
Particularly long drill cores with large cores have heavier weights. Preferably, the closure element is positive locked with the tool member so that larger drill cores cannot by their great weight independently push the closure element out of the tool member, especially when the tool is held vertically.
Removal of the entire drill core is then only possible if the inventive tool can reach to the base of the annular cutout. It is possible that parts of the fragmented drill core can impair complete penetration of the tool member to the base of the annular cutout. In order to assist the operator in ascertaining such a blockage, a measurement scale is arranged on the tool member and can assist the operator in checking, whether the member is at the base of the annular cutout.